The present invention relates to tab-and-latch mechanisms for a strap member for selectively and releasably coupling opposing ends of a strap by a mechanical device, and more specifically an improved seat-belt style tab-and-latch mechanism for a strap member wherein the strap member is part of limited release applications such as a pet collar, pet harness, pet muzzle, or any general purpose strap for any general purpose bag.
Seatbelt-style buckle mechanisms for selectively coupling and releasing two ends of a web-material, such as a seatbelt, are generally known in the art. In the prior art of seatbelts, it is very important that the latch, when closed, is secure under high impact loads, but it is equally important that the latch quickly and easily release with minimal effort or force when the wearer (or rescuer) needs to uncouple the restraint webbing. Accordingly, the current art teaches an over-extending release lip end on a cover of a latch buckle, with very little upward rotation of the cover relative to the frame for release of the internal latch from the female clasp. Typically, the cover only needs to travel 5-degrees to 20-degrees for the latch to release.
Other latch mechanisms include an exemplary seat-belt style tab and latch mechanism, such as the Quick Releasable Buckle for Safety Belts described by F. L. Davis in U.S. Pat. No. 2,710,999 issued on 1952 Feb. 28 wherein a buckle made up of a channel form body having freely operable take-up means at one end for holding the strap, and a normally closed but instantly releasable dog or pawl at the opposite end for securing the strap. The adjustable take-up for strap is shown as consisting of a pull bar riveted or otherwise firmly secured across and between the parallel sides or flanges of the channel shaped base, a second, strap deflecting bar similarly mounted but located nearer the end of the base and a movable loop holding bar adapted normally to seat in notches in the ends of the side flanges but free to be separated from the base for belt lengthening purposes. The opposite anchored strap is removably connected with the buckle body by having a plate secured to the free end of the same and which is provided with a projecting tongue portion of a width to enter between the side flanges of the buckle body and having an opening therein to receive the abruptly shouldered locking dog or lug extension. To enable instant, free release of the holding dog, a hand lever secured by rivets or other fastenings over the top of the cam, and this releasing lever is utilized as a cover and protective guard for the parts located between the sides of the base by extending it laterally, At its free end the releasing handle may be upwardly curved for convenient, quick grasp by the fingers.
Davis further instructs that the leverage provided by the handle is sufficient to enable release of the dog from the end plate with even a light pull, and the tension of the spring is sufficient to hold the dog closed against any accidental or unintentional release. This feature, however, for use in limited release applications such as a dog collar mechanism has certain drawbacks as the cover can easily be unintentionally caught when a pet-dog is running through bramble, or is rough-playing with other canines. Further, the quick-release nature, while important for use as a seatbelt, is not desired in a pet collar.
This overhanging cover design is well-used in the art of seat-belt latch release mechanism. For example, the Safety Buckle described by Higuchi in U.S. Pat. No. 3,760,464 issued on 1972 Sep. 25, similarly uses an easy-opening, single spring, extended lever-cover for quick-release of a seat belt. Notably, Higuchi includes a latch with biasing spring designed to release the tab in direct proportion to rotation of the cover.
Other designs, as exemplified in U.S. Reissue Pat. No. 26,754 of 1970 Jan. 6 to Fisher, have limitations due to their use as automobile safety belts. For example, Fisher teaches that safety belt buckles often employ relatively long, heavy, and therefore, cumbersome release handles. This has been a requirement to obtain sufficient mechanical advantage to effect opening of the buckle under load. Fisher, in an attempt to improve upon the then-state-of-the-art design of seatbelt buckles presents a relatively short, light and therefore easily assembled and operated release handle. However, Fisher's design is ill-suited for a buckle for a limited release application such as a pet collar because such a design would open too-easily and inadvertently when the pet was working or at play.
Yet other known designs, as taught for example by Blair in U.S. Pat. No. 5,123,147 issued on 1992 Jun. 23, include a U-shaped base having upstanding sidewalls that support a pin carrying a locking cam, a spring, and a handle: Lifting one end of the handle rotates the locking cam against the closed-biased spring. A clasp or plate on one end of a belt, inserted between the base sidewalls, clamps to a protrusion on the base by the spring-loaded cam when the handle is released.
Limitations of such known mechanisms when adapted for use in limited release applications such as a dog collar release mechanism include having a cam that releases in direct proportion with the opening of the cover handle and having an handle with an end extending beyond the housing to facilitate opening—such designs are ill-suited for these applications because the over-extending handle would be prone to catch on objects when the dog is working or playing, and the direct translation of movement of the handle to release the cam would result in inadvertent releasing of the tab: This would enable the collar to fall off the dog and would therefore present a danger to the dog or to the public, or both as the dog would no longer be under control of a leash connected to the collar.
Other limitations in the known art include single biasing member, which provides resistance for the cover or handle from unintentional lifting, but also provides biasing against the latch cam to secure the tab in the buckle. This biasing member results in a direct proportional lifting of the latch for quick release of the cam to release the tab: While this feature is very important for quick release of a seatbelt buckle under load (for example, after a crash), this feature, however, is counter-productive when used on a pet collar. Quite the opposite is desired, a pet collar should be difficult to open, particularly under load for obvious reasons, a dog being restrained under stress may pull strongly against the collar and under these circumstances it is very important to not release the collar. For example, if the dog is used in law enforcement, or for hunting, or even rough play, this common feature in the known art is not desired.
Thus, there remains a need for a seat-belt style tab and latch mechanism, adapted for use as a closure mechanism for limited release applications that includes features that prevent unintentional releasing of the tab from the latch, deter the release flap from unintentional movement during rough-play, work, or other high-energy activities.